It's enough to pass the exam. It's what I used, although I did have a little experience with Cisco gear before hand. However, it's nice to have some hands on with equipment if you plan on working in networking. It's almost certainly going to come up in a job interview, and being able to say that you've configured real live gear will help you. It also gives you the confidence to work on real gear.

GNS3 is good, and lots of CCNA/CCNP people will use it, since it's a lot cheaper than real gear especially in more complex topologies. VIRL is better, but obviously more expensive.

There are quite a few guides on setting up labs for CCNA and CCNP R+S. The short and skinny is that for CCNA R+S, you want 3 switches and 3 routers, and for CCNP R+S you want 4 switches, where 2 are layer 3 capable (3560, 3750 etc), and 4 routers all ideally on 15.2 or better - but 15.0 will work for 95% of things, and cables to plug it all together.

Just passed ICND2 today. Packet Tracer is definitely enough for ICND2. That coupled with Boson's test environment($100) and CBTNuggets($84/month) got me through the exam. I also had Wendell Odom's book, but I really only used that if I was having an issue wrapping my head around a particular subject.

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